1. Field of the Invention
The present invention relates to sweeping vehicles for sweeping roads or other surfaces.
2. Description of the Prior Art
Sweeping vehicles have been proposed with low pressure delivery and with a sweeping and picking up assembly having a suction mouth connected by a suction pipe with a rubbish separator or container. By means of suction applied to the mouth, sweepings fed from sweeping means mounted ahead of the mouth are picked up and delivered to the rubbish container.
The suction mouth normally comprises a duct extending at its extremity into a funnel shape or rectangular or other cross-section. With previously proposed arrangements, there occurs phenomenon which may be termed as a suction vortex effect and which causes small particles of dirt to be hurled, with a force depending on the strength and speed of the suction stream, from the suction zone of the mouth back on to the surface being swept so that they are not picked up. Effective sweeping and picking up can only be achieved by using additional aids.
In order to reduce the effects of this phenomenon, it has been proposed to provide the suction mouth, in addition to a conventional seal of an elastic material, with sealing elements such as strips of bristle. This arrangement does not, however, operate satisfactorily.
It has also been proposed to arrange air nozzles behind the mouth and which are supplied with air from the exhaust section of the fan producing the suction stream, the air discharged from the nozzles acting to prevent discharge of dirt particles from the suction zone. This arrangement requires a greater number of constructional elements and thus presents from a technical point of view an expensive solution. Further it is essential that the whole arrangement of suction mouth with jets shall be completely sealed behind the surface being swept since otherwise, in dry weather, the air blast, full of dust, will overflow to the outside. This effect is particularly likely to occur when uneven surfaces are swept as for example paved streets, and gutters, which is a disadvantage as the joints between the paving stones inevitably cause breakup of the air under the sealing elements which likewise encourages an outflow of the air blast. This previously proposed sweeping vehicle is thus limited to use on concrete roads or asphalted surfaces.